1. Field of the Invention
The present invention relates to a piezoelectric material and more particularly to a lead-free piezoelectric material. The present invention also relates to a piezoelectric element, a multilayered piezoelectric element, a liquid discharge head, a liquid discharge apparatus, an ultrasonic motor, an optical apparatus, a vibratory apparatus, a dust removing device, an image pickup apparatus, and electronic equipment, each including the piezoelectric material.
2. Description of the Related Art
In general, piezoelectric materials are ABO3 perovskite-type metal oxides, such as lead zirconate titanate (hereinafter referred to as “PZT”). However, PZT contains lead as an A site element, and its effect on the environment is regarded as a problem. Thus, there is a demand for piezoelectric materials of lead-free perovskite-type metal oxides.
One known piezoelectric material of a lead-free perovskite-type metal oxide is barium titanate. In order to improve the characteristics of barium titanate, materials based on barium titanate are being developed.
Japanese Patent No. 4039029 discloses a piezoelectric material in which part of the A site of barium titanate is replaced by Ca in order to reduce the temperature dependence of the piezoelectric property of the barium titanate. Japanese Patent Laid-Open No. 2010-120835 discloses a piezoelectric material in which Mn, Fe, or Cu is added to a material prepared by replacing part of the A site of barium titanate by Ca in order to improve the mechanical quality factor of the barium titanate.
However, such known piezoelectric materials have a low piezoelectric constant in a high temperature region and a low mechanical quality factor in a low temperature region in a device operation temperature range (−30° C. to 50° C.). The present invention addresses these problems and provides a lead-free piezoelectric material having a high piezoelectric constant and a high mechanical quality factor in a device operation temperature range. A piezoelectric material according to the present invention contains Sn and Bi and thereby has a high mechanical quality factor particularly at low temperatures.
The present invention also provides a piezoelectric element, a multilayered piezoelectric element, a liquid discharge head, a liquid discharge apparatus, an ultrasonic motor, an optical apparatus, a vibratory apparatus, a dust removing device, an image pickup apparatus, and electronic equipment, each including the piezoelectric material.